NFS performance over ASM?

In Netapp storage 11gr2 rac on linux using ASM on NFS versus 11gr2 rac on linux using nfs with out ASM. Please advise, which one is better interms of performance for DW. DB going to be around 20TB. Appreciate your reply..

Hi;
Please check below links which could heplful for your issue:
Using NFS with ASM…
http://www.oracle-base.com/blog/2010/05/04/using-nfs-with-asm/
Oracle NetApp white paper..
http://www.oracle.com/technology/products/database/asm/pdf/netapp_asm3329.pdf
http://kevinclosson.wordpress.com/kevin-closson-index/cfs-nfs-asm-topics/
Regard
Helios

Similar Messages

Solaris 10 NFS performance on Linux running ws3 update 3

Hope someone can help me sort out this problem.
Dear Support.
We are having a Solaris/Sparc file server running Solaris 10. The Solaris machine act as a NFS file server. We encounter very poor NFS performance when copying files to and from a filesystem via Linux NFS
I have set up a very simple test scenario. Created a tar file, size around 3 GB. The file is sitting on a SAN system. The file it self is created on a Solaris 10 UFS filesystem.
Solaris E240 Solaris 8 NFS, GB interface copy to and from the same disk via NFS
timecp /seis/seis600_new/usr.tar /seis/seis600_new/new1.tar
real 2m18.91s
user 0m0.11s
sys 0m29.72s
IBM/AMD 64 bit Linux WS3 U5, GB interface NFS to and from the same disk via NFS.
time cp /seis/seis600_new/usr.tar /seis/seis600_new/new1.tar
real 6m24.670s
user 0m0.130s
sys 0m21.860s
Also run the test on other Linux boxes with similar results?
The funny part of this is that I can reproduce the performance problem on other SUN systems among the SUN Blade 2000 with 8 GB Ram
Let me wrap up.
Always bad NFS performance when using NFS between Solaris NFS server and Linux client.
Not always bad performance when using NFS between Solaris server and clients.

It's been a while since I was doing linux->solaris nfs, so bear with me as I clear out the cobwebs.
First things to check: Mount options for the nfs mount to the server.
Which versions of nfs are you using?(v2, v3?) Solaris uses version 3 mounts by default.
What's your wsize and rsize for reads and writes?
I believe linux is limited to using 8k r/w block sizes. Solaris will let you use r/wsize up to 32k in nfsv3, which would really help with larger data transfers.
nfsv3 has a number of performance enhancements over v2, so give that a shot with a larger block size.
nfsvers=3,wsize=8192,rsize=8192,nolock,intr
Also experiment with your locking options, that might help some.
NFS has always been a fairly weak point for linux.
A few links for reference:
http://www.scd.ucar.edu/hps/TECH/LINUX/linux.html
http://nfs.sourceforge.net/
Cheers && good luck,
fptt.

NFS Performance

I have 2 questions about NFS on 10.4.
Client;
Has NFS performance improved on the client side? Last time I tested was 10.3, and the sustained throughput was about 10-12 MB/s on a gig connection. This was from a Sun NFS server.
Server;
Has the performance improved? I am thinking about doing an Xsan NFS re-share to 50+ Linux machines in a compute farm. Will this work out well?
I'm interested to hear from anybody doing heavy NFS serving.
Thanks,
David

The client is somewhat lacking.
On one test here (XServe G5 client talking to XServe RAID 5 array connected to XServe G5 NFS server) I get around 40MB/sec copying a file to the RAID over a gigabit ethernet network.
By comparison, a Solaris machine talking to the same server gets almost 80MB/sec.
So it sounds like it's improved some from when you last tested, but maybe not by as much as you'd like.
Note that these tests were done on a single active client (or maybe some minor background traffic going on at the same time).
As for the server side, I don't know quite where that tops out. A quick test here shows little difference in times even when multiple clients are writing to the RAID at the same time. The server might be able to keep up with the RAID speed.

NFS performance with Solaris 10

Hello,
We have been playing with one of the x4200s running s10u2, or snv_50 for that matter, and are getting terrible numbers from the NFS performance. Initially, we suspected it was just the ZFS filesystem on the back (which it was, though zil_disable made it a lot better), but even after exploring a little I am getting terrible numbers for NFS backed by UFS. Using afio to unafio a file on the disk gives:
Local:
afio: 432m+131k+843 bytes read in 263 seconds. The operation was successful.
Remote:
afio: 432m+131k+843 bytes read in 1670 seconds. The operation was
successful.
I have raised the ncsize to 1000000, and upped the server threads to 1024.
The same thing on a linux box(ext3) turns in local times of 100 seconds and remote at 180 seconds. The differences in the local and remote numbers are just crazy. The difference in the ZFS is way worse:
Local zfs:
afio: 432m+131k+843 bytes read in 137 seconds. The operation was successful.
NFS -> ZFS:
afio: 432m+131k+843 bytes read in 2428 seconds. The operation was
successful.
I have started looking into dtrace for tracking the problem, but don't have much to report yet.
Any suggestions appreciated.

Ask this on the Solaris Forum, not the Java Networking forum.
Edit: typo

ISCSI, AFP, SMB, and NFS performance with Mac OS X 10.5.5 clients

Been doing some performance testing with various protocols related to shared storage...
Client: iMac 24 (Intel), Mac OS X 10.5.5 w/globalSAN iSCSI Initiator version 3.3.0.43
NAS/Target: Thecus N5200 Pro w/firmware 2.00.14 (Linux-based, 5 x 500 GB SATA II, RAID 6, all volumes XFS except iSCSI which was Mac OS Extended (Journaled))
Because my NAS/target supports iSCSI, AFP, SMB, and NFS, I was able to run tests that show some interesting performance differences. Because the Thecus N5200 Pro is a closed appliance, no performance tuning could be done on the server side.
Here are the results of running the following command from the Terminal (where test is the name of the appropriately mounted volume on the NAS) on a gigabit LAN with one subnet (jumbo frames not turned on):
time dd if=/dev/zero of=/Volumes/test/testfile bs=1048576k count=4
In seconds:
iSCSI 134.267530
AFP 140.285572
SMB 159.061026
NFSv3 (w/o tuning) 477.432503
NFSv3 (w/tuning) 293.994605
Here's what I put in /etc/nfs.conf to tune the NFS performance:
nfs.client.allow_async = 1
nfs.client.mount.options = rsize=32768,wsize=32768,vers=3
Note: I tried forcing TCP as well as used an rsize and wsize that doubled what I had above. It didn't help.
I was surprised to see how close AFP performance came to iSCSI. NFS was a huge disappointment but it could have been limitations of the server settings that could not have been changed because it was an appliance. I'll be getting a Sun Ultra 64 Workstation in soon and retrying the tests (and adding NFSv4).
If you have any suggestions for performance tuning Mac OS X 10.5.5 clients with any of these protocols (beyond using jumbo frames), please share your results here. I'd be especially interested to know whether anyone has found a situation where Mac clients using NFS has an advantage.

With fully functional ZFS expected in Snow Leopard Server, I thought I'd do some performance testing using a few different zpool configurations and post the results.
Client:
- iMac 24 (Intel), 2 GB of RAM, 2.3 GHz dual core
- Mac OS X 10.5.6
- globalSAN iSCSI Initiator 3.3.0.43
NAS/Target:
- Sun Ultra 24 Workstation, 8 GB of RAM, 2.2 GHz quad core
- OpenSolaris 2008.11
- 4 x 1.5 TB Seagate Barracuda SATA II in ZFS zpools (see below)
- For iSCSI test, created a 200 GB zvol shared as iSCSI target (formatted as Mac OS Extended Journaled)
Network:
- Gigabit with MTU of 1500 (performance should be better with jumbo frames).
Average of 3 tests of:
# time dd if=/dev/zero of=/Volumes/test/testfile bs=1048576k count=4
# zpool create vault raidz2 c4t1d0 c4t2d0 c4t3d0 c4t4d0
# zfs create -o shareiscsi=on -V 200g vault/iscsi
iSCSI with RAIDZ2: 148.98 seconds
# zpool create vault raidz c4t1d0 c4t2d0 c4t3d0 c4t4d0
# zfs create -o shareiscsi=on -V 200g vault/iscsi
iSCSI with RAIDZ: 123.68 seconds
# zpool create vault mirror c4t1d0 c4t2d0 mirror c4t3d0 c4t4d0
# zfs create -o shareiscsi=on -V 200g vault/iscsi
iSCSI with two mirrors: 117.57 seconds
# zpool create vault mirror c4t1d0 c4t2d0 mirror c4t3d0 c4t4d0
# zfs create -o shareiscsi=on -V 200g vault/iscsi
# zfs set compression=lzjb vault
iSCSI with two mirrors and compression: 112.99 seconds
Compared with my earlier testing against the Thecus N5200 Pro as an iSCSI target, I got roughly 16% better performance using the Sun Ultra 24 (with one less SATA II drive in the array).

Cannot export nfs-share over ipv6 in OS X 10.8

I've successfully exported my nfs share over ipv4 and can access this with a nfs-client from a linux machine. However, I'm not able to export the same share over ipv6.
In my /etc/exports I have:
/Volumes/Harddisk
-network 10.0.0.0
-mask 255.255.255.0
/Volumes/Harddisk
-network fd60:760d:98ec:8588::/64
However, from the linux client I can only mount the ipv4 share, but not the ipv6 share.
Is it possible to export nfs-shares over ipv6 in OS X 10.8?

I would suggest testing a connection from a second Mac also running 10.8 via IPv6. At least then you know both will be using compatible versions. If that does not work then it would seem to be an IPv6 issue on the Mac server.

Using NFS file for ASM

hello to all
I am familar with ASM and NFS but I don't know what is mean of using NFS file for ASM
can you explain for me ? or do you know manual for this on WEB ?
thanks

I don't think ASM via NFS is optimal.
You need to create your NFS mounts. Then use dd to create files in your various NFS mounts and then present these files to ASM as disks.
try:
http://www.oracle.com/technology/products/database/asm/pdf/netapp_asm3329.pdf
jason.
http://jarneil.wordpress.com

FTP performance over NFS 3

Hi Guys,
I have a NFS mount from one solaris OS to another solaris OS, When i do FTP to the NFS mounted server i get disconnected during "cd" to one particular directory. There are 500000+ files in that directory of total size 50GB.
My NFS stat is as below. I will like to know if there is any way to cache the file count information on nfs client side or any way to improve the performance to resolve FTP issue.
---cut---
Flags: vers=3,proto=tcp,sec=sys,hard,intr,link,symlink,acl,rsize=1048576,wsize=32768,retrans=5,timeo=600
Attr cache: acregmin=3,acregmax=60,acdirmin=30,acdirmax=60
---cut---
Thanks
Rahul

Hi;
Please check below links which could heplful for your issue:
Using NFS with ASM…
http://www.oracle-base.com/blog/2010/05/04/using-nfs-with-asm/
Oracle NetApp white paper..
http://www.oracle.com/technology/products/database/asm/pdf/netapp_asm3329.pdf
http://kevinclosson.wordpress.com/kevin-closson-index/cfs-nfs-asm-topics/
Regard
Helios

Sharing DVD over NFS - performance question

Hi,
I'm trying to share the DVD over NFS.
I have updated /etc/rmmount.conf with the following line:
share cdrom* -o ro,anon=0Everything works well, except the reading speed, which is quite slow.
Copying a ~200MB file from DVD over NFS takes ~12 minutes.
Copying the same file from DVD to the local filesystem takes ~2 minutes,
and copying this file from the hard drive over NFS takes ~20 seconds.
This makes me believe that the issue is in the interworking of the NFS and DVD-ROM, for (hypothetical) example,
the disk can not spin up to the max speed due to the random access.
Has anyone tried sharing the DVDs with good performance? Should I read up and tweak some NFS parameters or abandon the idea of achieving good performance?
I'm using Solaris 10 Update 7.
Thanks in advance for any suggestions.

Thanks for the suggestion.
I'm not sure if it's applicable for my issue. From what I've read, it may help if the same data is read over and over,
but not with the reading speed of just inserted DVD disks which are not yet cached (which is the usage pattern I'm trying to optimize for).

Strange .nfs file in ASM storage

Hello
I'm using ASM in a RAC environment over NFS. I've noticed that where I've raw files for ASM I've also some .nfsXXXXXXXxx files:
[oracle@itsm-cldb1c oradata]$ ls -al
total 29417868
drwxrwxrwx 3 root root 4096 Aug 28 11:31 .
drwxr-xr-x 27 root root 4096 Aug 27 19:20 ..
drwxr-x--- 2 oracle oinstall 4096 Aug 28 08:58 dbs
-rw-r--r-- 1 oracle oinstall 10737418240 Aug 28 10:36 .nfs0011a52600000001
-rw-r--r-- 1 oracle oinstall 5368709120 Aug 28 11:21 .nfs0011a52700000002
-rw-r--r-- 1 oracle oinstall 4294967296 Aug 28 11:40 tdwdisk1
-rw-r--r-- 1 oracle oinstall 4294967296 Aug 28 11:40 tdwflash1
-rw-r--r-- 1 oracle oinstall 5368709120 Aug 28 11:39 tdwstorage1
[oracle@itsm-cldb1c oradata]$ rm -rf .nfs0011a52*
rm: cannot remove `.nfs0011a52600000001': Device or resource busy
rm: cannot remove `.nfs0011a52700000002': Device or resource busy
And these files are busy. Anyone knows what kind of files are them?
Thanks
Stefano

This usually happens if you are using NFS...and I think you are using NFS. If you remove a file that is currently/actively being used or open by running process , the file isn't really removed and it would manifest itself as a .nfsxxxx files.
HTH
Thanks
Chandra Pabba

Looking for help to improve Airport performance over LAN (WAN is fine)

Ok, I've read through several threads on this forum that address problems people are having with slow performance with Airport. I've also checked out all of the Apple KBs that address Airport, recommended settings. Unfortunately my issue isn't addressed by anything I've read to date.
The bottom line is that both download and upload performance between any of my devices and the internet is fine, no problems. I am paying for 30MBps download from Verizon FIOS, I routinely get 20, and I'm guessing that the delta is Verizon's problem, not my network's. However, streaming from my media server to another device on the wireless LAN is a different story entirely. I get somewhere between 1 and 2 MBps, tops, and this poses big problems for streaming music and movies.
My network is comprised of 3 Airport Expresses. One of them is a MC414LL/A model. This one is connected to my Verizon FIOS Actiontec MI424WR router (which I have set to bridge-mode according to the instructions provided at http://www.dslreports.com/forum/r17679150-Howto-make-ActionTec-MI424WR-a-network -bridge) via CAT5 ethernet. This Airport Express is set to "create a network" network mode, "802.11 only (5GHz) - 802.11b/g/n" radio mode (although I have also tried "802.11 only (5GHz) - 802.11/n only (2.4 GHz)" radio mode, and this didn't solve the problem). Finally, I have chosen 2.4 and 5GHz channels that have little interference (2 and 161 respectively). My other two Airport Expresses are MB321LL/A models and are set to "Extend a wireless network" network mode, with the 5GHz network chosen as the network that they extend. (I have tried switching over to having them extend the 2.4GHz network, and performance gets worse, not better.)
I am using a late 2009 Mac Mini as a media server. It is connected to the 5GHz network (though I've tried the 2.4GHz network), and it runs XBMC and JRiver media servers (not simultaneously, either one or the other.) I have a PS3 and a Sony Blu Ray player, each plugged into one of the MB321LL/A Airport Expresses via CAT5 ethernet, and I stream media to each of these devices via one or the other media server (both devices are DNLA-enabled). My Mac Mini has a 3TB external hard drive connected via FireWire 800, which is where all of my media resides. In addition to streaming media over the network, I have a TV plugged directly into the Mac Mini. When I play media to this TV, performance is outstanding, so I'm confident my poor performance to the PS3 and Sony BDP is a network issue, not an issue with the external drive.
Although my building has several other wireless networks, only one of them is 5 GHz, and it isn't using channel 161. The 2.4 GHz band is crowded with several networks, although channel 2 is usually in the clear. I have tried switching let Airport choose a channel automatically, and I haven't noticed a difference. It has occurred to me that the problem could be with how I bridged the Verizon Actiontec router and not with any of the Airports, but I don't get any errors (e.g. double NAT errors, which some people who have bridged improperly get), and I am pleased with my download and upload speeds to the internet. The issue is only on my LAN. Finally, yes, all of my firmware is up to date, version 7.6.3 on all three Airport Expresses.
Can anyone offer me suggestions for how I can get better performance streaming media from my server to the two playback devices? Since all 3 Airport Expresses support 5GHz, I'd have thought I'd be able to take advantage of 802.11n speeds when streaming between them. (MB321LL/A supports "Draft N", but does this matter?) With the settings that I'm currently using, I can't stream faster than 2MBps (and that's on a good day), which is below what I ought to be able to get rom 802.11g. This is especially problematic when I try to stream hi res (96 MHz / 24 bit or higher) music files, whether uncompressed or compressed. I hear awful pulsing sounds through my speakers. If I pause the track and let my streaming device buffer, I might get 10 or 15 seconds of clean playback, but then it starts the pulsing again as soon as the buffered music is finished playing. On occasion when I stream music from my iPhone via Airplay to one of the Airport Expresses, I get clean playback most of the time, but on occasion the music cuts out. (It's my understanding the Airplay requires ~800 Kbps, which seems consistent with my LAN speed usually being between 1 and 2 Mbps but sometimes dropping).
I have iStubler and I've used the Apple network diagnostics -- these are the tools that led me to choose channels 2 and 161 for 2.4 and 5GHz respectively. I'm sure I could be using these tools to learn more about my network's performance, but I'm sure what to look for.
Thanks for your suggestions.

Ok, cool. I'm really glad that the issue has been isolated. Thanks a ton for your insight!
Hopefully I can find a spot where the signal strength of the hub is noticably better but that isn't too inconvenient for an ethernet run. My Sony BDP, which is the device connected to the problem basestation, has wifi capability, so I could always ditch the ethernet cable if the best spot for the basestation doesn't permit a cable run. But I'm aware that ethernet usually offers faster transfer speeds than wifi. Moreover, I'm not sure that the Sony BDP supports 5GHz. It might be a 2.4GHz-only device, in which case I'll have new interference issues to contend with, since like I said in my original post, there are several other 2.4GHz networks in my building.
Anyhow, now that I understand the problem, I can figure out a solution. Thanks again.

How can I improve performance over a Branch Office IPsec vpn tunnel between and SA540 and an SA520

Hello,
I just deployed one Cisco SA540 and three SA520s.
The SA540 is at the Main Site.
The three SA520s are the the spoke sites.
Main Site:
Downstream Speed: 32 Mbps
Upstream Speed: 9.4 Mbps
Spoke Site#1:
Downstream Speed: 3.6 Mbps
Upstream Speed: 7.2 Mbps (yes, the US is faster than the DS at the time the speed test was taken).
The SA tunnels are "Established"
I see packets being tranmsitted and received.
Pinging across the tunnel has an average speed of 32 ms (which is good).
DNS resolves names to ip addresses flawlessly and quickly across the Inter-network.
But it takes from 10 to 15 minutes to log on to the domain from the Spoke Site#1 to the Main Site across the vpn tunnel.
It takes about 15 minutes to print across the vpn tunnel.
The remedy this, we have implemented Terminal Services across the Internet.
Printing takes about 1 minute over the Terminal Service Connection, while it takes about 15 minutes over the VPN.
Logging on to the network takes about 10 minutes over the vpn tunnel.
Using an LOB application takes about 2 minutes per transaction across the vpn tunnel; it takes seconds using Terminal Services.
I have used ASAs before in other implementation without any issues at all.
I am wondering if I replaced the SAs with ASAs, that they may fix my problem.
I wanted to go Small Business Pro, to take advantage of the promotions and because I am a Select Certified Partner, but from my experience, these SA vpn tunnels are unuseable.
I opened a case with Small Business Support on Friday evening, but they couldnt even figure out how to rename an IKE Policy Name (I figured out that you had to delete the IKE Policy; you cannot rename them once they are created).
Maybe the night weekend shift has a skeleton crew, and the best engineers are available at that time or something....i dont know.
I just know that my experience with the Cisco TAC has been great for the last 10 years.
My short experience with the Cisco Small Business Support Center has not been as great at all.
Bottom Line:
I am going to open another case with the Day Shift tomorrow and see if they can find a way to speed things up.
Now this is not just happening between the Main Site and Spoke Site #1 above. It is also happeninng between the Main Site and Spoke #2 (I think Spoke#2 has a Download Speed of about 3Mbps and and Upload Speed of about 0.5 Mbps.
Please help.
I would hate to dismiss SA5xx series without making sure it is not just a simple configuration setting.

Hi Anthony,
I agree!. My partner wants to just replace the SA5xxs with ASAs, as we have never had problems with ASA vpn performance.
But I want to know WHY this is happening too.
I will definitely run a sniffer trace to see what is happening.
Here are some other things I have learned from the Cisco Small Business Support Center (except for Item 1 which I learned from you!)
1. Upgrade the SA540 at the Main Site to 2.1.45.
2a. For cable connections, use the standard MTU of 1500 bytes.
2.b For DSL, use the following command to determine the largets MTU that will be sent without packet fragmentation:
ping -f -l packetsize
Perform the items below to see if this increases performance:
I was told by the Cisco Small Business Support Center that setting up a Manual Policy is not recommended; I am not sure why they stated this.
3a. Lower the IKE encryption algorithm from "AES-128" to DES.
3b. Lower the IKE authentication algorithm to MD5
3c. Also do the above for the VPN Policy
Any input is welcome!

Performance over DG from mysql to oracle very slow for inserts

configured het services over gateway from oracle 11.2.0.4 to mysql 5.6
Have a table I want to pull over into oracle. 1000 rows.
On mysql : create view vw_mysql_t1 as select columns from my_mysql_table.
On Oracle: create view vw_ora as select columns from vw_mysql_t1@mysql_link
On oracle: select * from vw_ora data returns data in 3-4 seconds.
however, try an insert to get the data over
     insert into a_table_on_oracle
         (select * from vw_ora)
takes 11-12 minutes.
create table as or insert into same performance. Tried just inserting 1 row and same performance 11-12 minutes. any ideas?

cant seem to get the trace file to generate. any ideas, I have the config as below, the gateway is working, I can select data no problem from table@dcv   , just performance is terrible
logfile not in $ORACLE_HOME/hs/log
or
/tmp
this is my tns
dcv =
(DESCRIPTION =
    (ADDRESS = (PROTOCOL = tcp)(HOST = <IP of server>)(PORT = 1521))
    (CONNECT_DATA =
      (SID = dcv)
    (HS = OK)
this is my init file
# HS init parameters
HS_FDS_CONNECT_INFO=dcv
HS_FDS_TRACE_LEVEL=255
HS_FDS_SHAREABLE_NAME = /usr/lib64/libmyodbc5a.so
HS_RPC_FETCH_SIZE=50000
HS_ROWID_CACHE_SIZE=10000
#HS_LONG_PIECE_TRANSFER_SIZE=1024
HS_LONG_PIECE_TRANSFER_SIZE=65536
HS_LANGUAGE=AMERICAN_AMERICA.WE8ISO8859P15    ## The Oracle RDBMS is using a Unicode characterset [ID 756186.1]
HS_FDS_FETCH_ROWS=1                           ## This is select int datatype
HS_FDS_SQLLEN_INTERPRETATION=32               ## This is to select NULL values via DB Link [ID 554409.1]
# ODBC specific environment variables
set ODBCINI=/etc/odbc.ini
more /etc/odbc.ini
[dcv]
Driver       = /usr/lib64/libmyodbc5a.so
SERVER       = <IP of mysql server>
PORT         = 3306
USER         = un
Password     = pw
Database     = dcv
OPTION       = 3
CHARSET      = latin1
[ODBC]
TRACE        = ON     # also tried 0 and 1 and DEBUG and USER
TraceFile    = /tmp/odbc.trace
10:11:19 SQL> select count(*) from "vw_t1"@dcv;
COUNT(*)
     24794
Elapsed: 00:00:00.23
10:11:45 SQL>
10:11:57 SQL>
10:11:57 SQL>
10:11:57 SQL>
10:11:57 SQL>
10:11:58 SQL> create table backup_data.delete_me as
10:11:59   2 select   * from
10:11:59   3        "vw_t1"@dcv;
Table created.
Elapsed: 00:09:47.07
10:21:49 SQL>
Theres around 130 columns, varchars, numerics and floats. Is there a conversion going on that would take that long?

Confusion over ASM

Hi All,
i was going through ASM docs and so far my understanding " its is purely an instance which has got only the metadata of all the RDBMS instances using that ASM"
In ASM instance we dont have redo log file, datafiles etc then what is the functionality of DBWr and LGWr background processes in ASM instnace?
Regards,
ASM

Hans Forbrich wrote:
Aman,
Even I started with the misinterpretation that ASM handles I/O for the database. Not quite correct.
In the simplest explanation of ASM I've come up with is: Actual database I/O is 'raw', with the benefit that ASM manages the table of contents of the disk. The database server process asks ASM where to start reading; the DBWR asks ASM where to start writing - both server process and DBWR still operate.
"The Oracle ASM instance manages the metadata and provides space allocation for the Oracle ASM files. When a database instance creates or opens an Oracle ASM file, it communicates those requests to the Oracle ASM instance. In response, the Oracle ASM instance provides file extent map information to the database instance."
This is taken from the 11gR2 ASM manual in Chapter 1 http://download.oracle.com/docs/cd/E11882_01/server.112/e10500/toc.htm at Fig 1-1
Hans,
Thanks so much for the correction and for the link. I stand corrected, ASM does teh metadata writes only, the actual data IO operations are handled by the db's background processes only.
Just now, I opened [ASM Under the Hood book|http://www.amazon.com/Oracle-Automatic-Storage-Management-Under/dp/0071496076] and was reading it to find the answer and page no 44 clearly mentioned the same what you have just said. Here is a note from the same page about DBWR ,
>
This processes manages the SGA buffer cache in the ASM instance. DBWR writes out dirty buffers ( changed metadata buffers ) from ASM buffer cache to disk. >
Which I believe is a very clear explanation that ASM processes just maintain metadata stuff. Thanks so much once again!
@Gurfan, Eduardo,
Apologies for any confusion that I unknowingly have created. Please read Hans's reply and mine over here.
regards
Aman....
Edited by: Aman.... on Oct 10, 2009 7:24 AM corrected page no, it was 44 :-( .

Slow Performance Over time, Drawing Access Forms

we've been using a small access database for almost a year now, written from scratch using only Access 2013
over time drawing of one of the forms slows right down, once the form is draw its fine, but if you switch to a different form at the top then switch back it draws slow, maybe 7-8 seconds compared to the usual 1 second, sometimes it can work all day no problem,
sometimes after an hour it starts drawing the form slow, the only way to cure it is to restart the machine.
Logging off and logging back on doesn't cure it, only restarting it, it does get restarted every night automatically as an attempt to help the problem
this happens on 2 machines, both have intel HD graphics, (previously one was using a NVidia GT 250 which had appalling performance in design mode (even with hardware acceleration disabled) so we switched to the on-board, although this issue happens
with both machines)
Back end gets compacted/and repaired every night on a schedule as I did notice a big slow down if you let that go a couple of weeks, I've decompiled/recompiled the front end, short of re-writing the form I'm not sure what to do, it does have a lot of controls,
around 30 textboxes 1 combo box + 20 or so labels and 4 buttons, one embedded report, it only happens on this one form, I have embedded reports in other forms which don't have the same issue and have the same number of controls.
I'm a bit of a loss, its not a huge issue, but just an annoyance, when I get time I'm tempted to try recreating the form from scratch, but there is a lot of VBA code behind it, before trying that just wondering if there are any suggestions to improve performance?
*edit* the form is loaded from a list of customers, so it gets opened closed a lot, I thought simply hiding the form instead of loading/unloading all the time would speed it up, it does slightly improve the speed after viewing the second lot of details,
however it suffers the safe fate of slowing down over time, it seems to be only drawing the form and not accessing the db

I think you would benefit from a code review by a strong Access developer. What you are describing is not normal and may be caused by systematic programming choices.
-Tom. Microsoft Access MVP
Just wondering, once this does happen going into design mode on any form is slow to draw, but only the one form at runtime once it starts happening.
the only visible difference apart from waiting is seeing the 'property sheet' on the right hand side gets visibly drawn left to right on any form once this happens, switch back to form view you see it get wiped out slowly, fade from left to right as it blanks
the form out
I had this 'slow' behaviour constantly with the NVidia card in one of our machines, even on new blank databases.
I'm not even sure if this is linked to the form I've made or not, its just the only reason I notice it is that it's frustrating to use.
Is this code review idea something that people volunteer to check or is it a paid service?

NFS performance over ASM?

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